1. Field of the Invention
The present invention relates to a plasma tube array-type display sub-module that realizes a large-screen plasma tube array-type display device joining the plurality of plasma tube array-type display sub-modules to one another, and a display device made of the plasma tube array-type display sub-module thereof. More specifically, the present invention relates to the plasma tube array-type display sub-module that allows to narrow a gap width between the adjacent plasma tube array-type display sub-modules joined to each other, and the display device made of the plasma tube array-type display sub-module thereof.
2. Description of the Related Art
As a technology for realizing a next-generation large-screen display device, a plasma tube array-type display sub-module has been developed with a structure that a plurality of plasma tubes each filled with a discharge gas is arranged in parallel. For example, a large-screen display device having a scale of several meters by several meters in size can be constructed of a plasma tube array-type display system module that the plurality of plasma tube array-type display sub-modules of 1 square-meter in size is joined to one another. The display device of such a type that the plurality of plasma tube array-type display sub-modules is joined to one another does not need either a large glass substrate to be handled, like an LCD, a PDP and the like, nor a large-scale facility and achieves even image quality at low cost. FIGS. 1A and 1B are schematic views each of which shows a specific example of a method to manufacture a conventional large display panel.
As shown in FIG. 1A, first, a plurality of plasma tube array-type display sub-modules 30a (front view) and 30b (back view) and the like is integrated with a sub-module frame and joined to each other with data IC substrates 30c, 30c, . . . attached on the back side to construct a display system module for a large screen. As shown in FIG. 1B, then, an X drive circuit 30d, a Y drive circuit 30e, and a component 30f including a controller, a power supply circuit and the like are incorporated in the display system module. Thus, a large display panel can be manufactured. Accordingly, it is possible to provide a large-screen display device that requires no large-scale facility investments and achieves even image quality. FIG. 2 is a perspective view which shows a schematic configuration of a plasma tube array of a conventional plasma tube array-type display sub-module.
As shown in FIG. 2, a conventional plasma tube array has a configuration that a plurality of plasma tubes 1, 1, . . . is arranged in parallel between a front-side supporting sheet 11 and a back-side supporting sheet 12, a plurality of display electrode pairs 2, 2, . . . each consisting of an X electrode and a Y electrode is formed on a rear surface of the front-side supporting sheet 11 so as to be orthogonal to the plasma tubes 1, 1, . . . and a plurality of address electrodes 3, 3, . . . is formed on an upper surface of the back-side supporting sheet 12 along the longitudinal direction of respective plasma tube 1. The plasma tube 1, in the shape of a thin tube, includes a phosphor layer (not shown) inside, and filled with a discharge gas. Moreover, an intersection of each address electrode 3 and each display electrode pair 2 is defined as a unit light emission region or discharge cell (refer to JP 2003-338245 A).
Typically, a large-screen plasma tube array-type display device can be constructed as follows. That is, a plasma tube array-type display sub-module is prepared in such a manner that a plasma tube array is integrated with a structural body called a sub-module frame of a certain size. Then, the plurality of plasma tube array-type display sub-modules is joined to one another. Herein, the “plasma tube array-type display sub-module” refers to a display film component as described above which includes a plasma tube, that is, a semi-finished product of a display device, which does not have a drive circuit, a power supply circuit and the like incorporated.
In a case where the plasma tube array-type display sub-modules are joined horizontally to one another, however, interconnections for supplying drive power to the display electrode pair 2 and interconnections for establishing a connection from an electromagnetic wave shield layer to a ground electrode must be formed separately. The drive power is supplied in the form of an AC high voltage. Therefore, the interconnections for supplying the drive power must be formed at a predetermined distance apart from the interconnections for establishing the connection to the ground electrode, which requires a connector mechanism with a complicated structure for the joining portion thereof. FIGS. 3A and 3B are schematic sectional views on the side orthogonal to the plasma tubes each of which shows a configuration of a front optical filter group 20 of a plasma tube array-type display sub-module constructing a conventional display device. The optical filter group 20 has multi-layered construction which generally comprises a color adjusting layer 22, an infrared absorbing layer 23, an electromagnetic wave shield layer 24 and an anti reflection layer 25. Further, a black stripe layer may be incorporated. As disclosed in JP 2001-141972 A, for example, a conventional PDP (Plasma Display Panel) requires a complicated mechanism in order to assemble the optical filter group including an electromagnetic wave shield. In accordance with above conventional PDP, as shown in FIG. 3A, the front optical filter group 20 specially prepared for a large screen must be commonly attached to a front-side frame housing (not shown) or surfaces of the front-side supporting sheets 11, 11, . . . of the plasma tube array-type display sub-modules joined to one another. Accordingly, the front optical filter group 20 must be optimally designed in accordance with a combination of the plasma tube array-type display sub-modules. Further, in a case where the front optical filter group 20 is attached directly to the front-side supporting sheet 21, the display device can not be disassembled into respective plasma tube array-type display sub-modules. For this reason, it causes difficulties to dismantle in a case where installed at an event venue and the like.
In order to solve this problem, as shown in FIG. 3B, a technology has been developed to form the front optical filter group 20 for each plasma tube array-type display sub-module. However, there has been a following problem. That is, a non-display region is subject to be formed at certain intervals between the adjacent plasma tube array-type display sub-modules joined to each other. Further, the joining portion between the adjacent plasma tube array-type display sub-modules becomes twice greater in thickness than the front optical filter group 20, resulting in a high possibility that the joining portion is displayed as a black line on a screen display by the width extended where no light is emitted in the joining portion.
Moreover, it may be considered that an end of the front-side supporting sheet 21 is bent toward the rear side space between the adjacent sub-modules so that the display electrode pairs 2, 2 are connected electrically to each other and the electromagnetic wave shield layers 24, 24 are also connected electrically to each other on the back side of a display screen. Therefore, a certain gap width generates between the adjacent sub-modules corresponding to a certain thickness of the front-side supporting sheet 21 and the optical filter group 20. Accordingly, a non-display region at certain intervals is inevitably formed between the adjacent plasma tube array-type display sub-modules joined to each other. If the formed non-display region is larger than a clearance between the adjacent plasma tubes 1 and 1, a region which brightness is darker than the surroundings generates at the joining portion between the adjacent plasma tube array-type display sub-modules. Consequently, there is a possibility that the joining portion between the adjacent plasma tube array-type display sub-modules is displayed as a black line on the screen.